In recent years, light emitting devices of an optical semiconductor (for example, a light emitting diode or LED) are diffused in place of an incandescent lamp or a fluorescent lamp. Of light emitting devices of a white LED, a light emitting element capable of emitting blue light and a mode using a resin containing a phosphor capable of converting blue light to yellow light are the mainstream.
In general, examples of a method for fabricating a white LED include a method for coating an LED chip with a phosphor-containing resin and a method for potting a phosphor-containing resin on a cup-shaped LED device. Also, for example, in an optical semiconductor device of Patent Document 1, a phosphor cover formed by injection molding of a phosphor-containing resin is used, and it is reported that it becomes possible to dispose the phosphor thin over the whole of the outside of a package by this cover, a light extraction efficiency from a chip is enhanced, and light scattering by the phosphor is inhibited, thereby enabling one to obtain desired light directivity.
On the other hand, from the viewpoints of handling properties and throughput, a method for undergoing molding using a sheet-shaped phosphor-containing resin layer is preferable. It is preferable to use a sheet obtained by laminating an encapsulating layer and a phosphor-containing resin layer (phosphor-containing layer) and so on as such a sheet, and by undergoing molding from the top of the sheet using a metal die, it becomes possible to dispose the phosphor over the whole of the outside of the package.
Patent Document 1: Japanese Patent No. 3678673